[gtkmm] NEWS: mention the new API list

[Murray Cumming <murrayc src gnome org>]

commit dd6023b48de88ddd15aa83df5e0ceb15b2125270
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Apr 6 16:05:54 2011 +0200

    NEWS: mention the new API list

 NEWS |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/NEWS b/NEWS
index 6fcb52e..979b699 100644
--- a/NEWS
+++ b/NEWS
@@ -49,6 +49,8 @@ General:
 * gtkmm-3.0 currently has no deprecated API.
   Not even API that was added and then deprecated during GTK+ 3.0.
 
+See also the list of new API in gtkmm 3.0:
+http://developer.gnome.org/gtkmm/unstable/since_3_0.html
 
 3.0.0 (unstable):